rpc: Retry select() if it is interrupted

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
rcld: Use clEnqueueFillBuffer to initially fill buffer

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>
rcld: Minor optimizations in rcl_proc.c and clproc.c

Signed-off-by: Pawel Dziepak <pdziepak@quarnos.org>